Insect pathogenic nematodes of families Heterorhabitidae and Steinernematidae are known to be symbiotically associated with bacteria of the genus Xenorhabdus. It has been observed that these bacteria have the ability to inhibit the activity of other bacterial growth.
International Application No. PCT/AU83/00156 (WO84/01775) discloses certain lipid soluble antibiotics isolated and characterised from cultures of the genus Xenorhabdus. The disclosures of that application are incorporated herein by reference.